Miner tram control circuit

ABSTRACT

A fluid control circuit for use in a mining machine tram system whereby there is provided a protection control to prevent undesired movement of a mining machine and a selective range of speed controls as may be required under different operating conditions. A plurality of interlocked valve mechanisms are utilized with a means of limiting operation of certain valves when control of a slow speed range is desired.

United States Patent 1 1 it I Ziegler et al. 1 i Oct. 22, 1974 [5 MINER TRAM CONTROL CIRCUIT 2.941.609 6/1960 Bowers m al. 611/53 R x 2,961,82 11/1960 Wisenbach 60/53 R [761 Inventors: H f 5 3,292,723 12/1966 Pinkerton et 61.... 60/53 A x 4 Glenn Dally, 1, Utlca, 3,383,857 5/1968 Rujchcl ct al 60/53 A 16362 3,398.53] 8/1968 Swanson ct al 60/53 A 3,625,637 12/1971 KiWflllC ct al. 60/52 vs [22], y 1973 3.768.263 /1973 01466 ct ul ..60/427 [2]] App]. No.: 377,342

Related U S Application Data Primary ExaminerEdgu r W. Geoghcgan [63] Continuation of Scr. No. l8l.()87. Sept. [6. l97l.

abandoned. [57] ABSTRACT I A fluid control circuit for use in a mining machine 52 us. c1 ..60/327,660;1428(266(g;2876, tram System whereby there is provided a protection [51] Int Cl Flsb 18/00 control to prevent undesired movement of a mining [58] Field of Search 421 427 48 4 486 machine and a selective range of speed controls as 60/327 447 420 80/6 may be required under different operating conditions.

I A plurality of interlocked valve mechanisms are utilized with a means of limiting operation of certain [56] References valves whencontrol of a slow speed range is desired.

UNITED STATES PATENTS 1 2,443,345 6/1948 Ernst 60/52 vs 5 Clalms, 2 Drawing Figures 32, I e m/ma L//vEs j 34 5 1/ J 30 42 30 34 46 44 gP/s I9 48 24 /UREV 24 TRA/MPUMP 5 -/4/?El/. 26 ma 2a SHUTTLE VALVE 0 6: -58 I I 72 TWOPOS/flO/VSELECMR VALVE I04 CHARM 74 CHARGING L/IVE PUMPS 94 1 1- as 90v 9 60. -EE 9a 7a 00uELEAcr/n/a 82 P/Lar c/-/Ec/r 74 VALVE a0 \7/ sL/PPLY LINES r L1. 9

e4- PRESSURE TWO PUS/T/O/V Fou CONTROL war F007 VALVE VALVE as 647 '4) RELIEF V4LVE$ -/2 TRAM l5 7 I 1 MINER TRAM CONTROL CIRCUIT This is a continuation, of application Ser. No. 181,087, filed Sept. 16, l97l now abandoned.

' BACKGROUND OF INVENTION Tram control of the track chains used on mining equipment is predominately accomplished by hydrostatic controls wherein hydraulic transmission lines are interconnected with val'ving to control hydraulic pumps and motors to regulate tram speed of continuous miners. Manually operated levers are utilized to position control pistons to effect selected speeds of tramming operation. It has been realized that under different operating conditions it is necessary to select speed changes in different increments of change. When moving a miner from one location to another the speed changes are not as critical as when moving the miner while sumping at a working face, therefore it is desirous to have an option of speed ranges in which different speed changes can be selected. Manually operated levers have heretofore been known to permit an undesired creeping motion of tram operation when a positive standstill is desired.

SUMMARY OF INVENTION According to the present invention there is provided a new and improved tram control circuit including a speed range control piston selectively operated to affect a speed control rapidly over a wide range or affect a very close control of speed in alimited slow speed range. The control circuit also includes a novel creep control with an interlocked valve arrangement whereby speed control is locked at a zero speed without simulta neous manual operation of a plurality of cooperatively acting valves.

Other provisions of the present invention will become more apparent when taken in conjunction with the accompanying detailed description and the drawings wherein:

FIG. 1 is a schematic view of the hydraulic control system included the individual interconnected valves, pumps and motors in outline;

FIG. 2 is outline view of a conventional rotary pump partly in section with a limiting cylinder included.

DESCRIPTION Referring to FIG. 1 there is shown a hydraulic control circuit for a miner having a constant speed hydraulic pump for driving a constant displacement hydraulic motor 12 on the left side of the miner and a constant speed hydraulic pump 14 for driving a constant displacement hydraulic motor 16 on the right side of the miner. The motors l2 and 16 each in turn drive their individual tracks (not shown) respectively on the left and right side of the miner by conventional gearing means not shown.

In that the pump and motor combinations are similar,

.a single set of reference numerals is utilized hereinafter for similar elements. The pumps 10 and 14 are of the conventional constant speed, reversible type shown in FIG. 2 each one having a rotary barrel l8 driven by electric motors 19 (FIG. 1), and a variable inclined cam plate 20 operating intake and output pistons 22 in accordance with the angle of inclination of the cam plate 20. Variations in the supply of fluid under pressure to an internally located control piston 24 changes the positioning of the piston 24 to vary the angle of inclination of cam plate 20 to in turn regulate thep'ump displacement which determines the speed of operation and direction of operation of motors 12 and 16 in a conventional manner. Reversal of the angle of the inclination of the cam plate 20 affects reversal of the function of the pistons 22 such that the intake function becomes an output function and vice versa to in turn effect reversal of the direction of operation of the associated motor 12 or 16. Control of the positioning of a control piston 24 is affected by a rotary valve 26 (FIG. 2) within the pump under the control of lever 28 (FIG. I). The lever 28 (FIG. 1) is positioned by a selfcentering double-acting cylinder device 30 (FIG. I) operative to different lever operating positions responsive to variable pressures in control lines 32 and 34 for each of said cylinder devices 30. The supply of fluid under pressure to.one or the other of the control lines 32 and 34, one being charged the other being vented to a reservoir 33 by lines 35, is selectively controlled by positioning of levers 36 and 38 of a manually operated two bank variable pressure control valve 40 located at the operators station. Supply of fluid under pressure to lines 32 and 34 controls operation of the two cylinder devices 30. The determination of which track is moved, at what speed it is moved, and in which direction it is moved is dependenton which of the levers 36 and 38 are moved, in what direction they are moved, and how far they are moved in a conventional tram control manner. The valve 40 is a conventional pressure control valve shown as the two lever controls in the outline box 40 where for example a predetermined degree of movement of a lever 36 varies the fluid under pressure from a source described hereinafter to the lines 32 and 34 to the cylinder device 30 to vary the pressures in respective chambers 42 and 44 thereof. The regulation of the pressures in chambers 42 and 44 regulates the position of a piston 46 and connecting rod 48 to position the lever 28, which in turn positions the regulating valve 26 (FIG. 2). The regulating valve 26 selects predetermined fluid pressure deliveries to the control chambers 50 and 52 of the internal control piston 24 which in turn determines the angle of inclination of the cam plate 20. Variation of the angle of cam plate 20 varies the intake fluid of the pumps. Such intake to the pump is supplied through lines 56 which communicate between a reservoir '54 and a usual charaging pump 58. The fluid is then pressurized and supplied via lines 60 and 62 through a high pressure relief valve 64 to the respective motors. Variation of the pressure supplied to the motors effects variation 'of the speed and direction of tramming of the miner through a drive shaft 66.

It can thus be seen that the pumps operate in a conventional manner wherein positioning of the control piston 24 regulates the position of the cam plate 20 which in turn regulates the output of the pump and thus the speed and direction of motor operation.

The use of a charging pump 58 at the intake to the pump, supplies sufficient fluid to make up for leakage and supply low pressure fluid for operating the pump control.

Associated with the just described pumping circuit is a control circuit comprising feed lines 68 and 70 supplying fluid under pressure from the charging pumps 58 to a double check shuttle valve 72 where the higher pressure delivered by the two feed lines is effective to block off the lower pressure and is delivered vvia a charging line 74 to a two position mechanically opertions with the pedal 78 in a non-depressed position (flow through valve 76 when pedal 78 is in a nondepressed position is indicated on FIG. 1 by solid arrowed lines within the rectangle designated 76); the fluid under pressure delivered thereto from charging line 74 is fed directly therethrough and via line 80 to a double acting pilot check valve 82 to operate internal check valves (not shown) to permit the relief valves 64 of the pump motors l2 and 16 to vent via lines 84 and 86 to the valve 82 and then to a reservoir 88, a condition in which the motors 12 and 16 do not run. Also while the pedal 78 is in its non-depressed position, a deliverry line 90 leading to the control valve 40 is vented through the foot valve 76 to a reservoir 92.

When the pedal 78 is depressed (flow through valve 76 when pedal 78 is depressed as indicated on FIG. 1 by dotted arrowed lines within the rectangle designated 76), the line 80 leading to the valve 82 is vented through the pedal operated valve 76 to the reservoir 92 thereby permitting the check valves (not shown) within the valve 82 to seat and stop the venting thereat, while the charging line 74 is connected through the pedal operated valve 76 to pilot lock line 94 to lock the internal check valves of valve 82 in a position to permit a pressure buildup in the lines 84 and 86 and the relief valves 64 to permit the motors to run. Simultaneously, the fluid under pressure in line 74 is supplied to the delivery line 90 and thence to the control valve 40 to act as a source of control pressure for the lines 32 and 34 as desired as described hereinafter.

Associated with the control circuit just described, is a speed selector circuit including a line 94 from the charging line 74 to a two position selector valve 96 with a selector lever 98 (flow through the valve indicated by the solid arrowed line in FIG. 1). In one position of the lever 98 the fluid under pressure from line 94 is supplied to selector line 100 and then to each pump volume control at a chamber 102 in a limiting cylinder 104 connected to the control chamber 50 and the control piston 24. Supply of fluid under pressure in chamber 102 acts on a limiting piston 106 having an adjustable stem 108 which moves against the control piston 24 to limit the travel thereof and thereby limit the volume range of the pumps and 14 and thus limit the speed range of the motors l2 and 16 as hereinafter described.

When the selector lever 98 is in a second position (flow therethrough indicated by the dotted arrowed line in FIG. 1), the selector line 100 is vented therethrough to a reservoir 110 to vent the limiting cylinder 104 and prevent the described limiting of the movement of control piston 24 thereby restoring the full volume and speed range to the pump and motor drive system, respectively, as described hereinafter.

It should be noted that although numerous reservoirs 33, 54, 88, 92 and 110 are shown for convenience of description, it is necessary to'have only one reservoir with the appropriate lines connected thereto.

OPERATION From the foregoing description it can be seen that there is no motor operating control until the foot pedal 78 is depressed. Prior to depression of the foot pedal 78, the delivery line is vented to the reservoir 92 thus there is no supply of fluid under pressure for the control levers 36 and 38. Also, the supply of fluid under pressure from the charging line 74 is through the foot valve 76 to line 90 and thence to pilot check valve 82 wherein internal check valves (not shown) are opened to permit venting (to reservoir 88) of relief lines 84 and 86 and the relief valves 64 on the two motors l2 and 16 thereby preventing an operative buildup of fluid under pressure at the motors to prevent 'any undesired creeping or movement of the miner.

Depression of the foot pedal 78 permits a supply of fluid under pressure from the charging line 74 to the delivery-line 90 and thence to control valve 40 where such fluid under pressure is utilized as desired by manipulation of the control levers 36 and 38, to supply fluid under pressure to the control lines 32 and 34 and effect the conventional control-of pump and motor system as desired. Depression of the pedal 78 also effects cut-off of the venting of the check valves (not shown) of valve 82 and locks the internal valving (not shown) such that an operating pressure buildup occurs in the relief lines 84 and 86 and relief valves 64 to permit operation of the motors.

The speed range of the pump and motor system is determined by the positioning of the control piston 24 (FIG. 2) in the conventional manner. When it is desired to reduce the speed range, the lever 98 of selector valve 96 is moved to the position shown in FIG. 1 wherein fluid under pressure is supplied therethrough from the charging line 74 to a control line 100 to act on the limiting piston 106 in the limiting cylinder 104 in a manner that the adjustable piston stem 108 thereof is moved into the operating space of the control piston 24 to thereby limit the movement of the control piston 24 to the left which in turn according to conventional operating procedures will limit the operating output range of pumps in the forward direction and thereby prevent excessive undesired speeds of the miner while sumping.

It is to be noted that modifications can be made to the preferred embodiments described hereinabove without departing from the scope of the invention herein; for example selector valve 96 is described hereinabove as being manually operable by means of lever 98, however, a pilot operable valve can be substituted therefor which is made operable by pressure responsive or electrical means, and the like.

What is claimed is:

1. A method of controlling the tramming rate of a mining machine having a constant speed hydraulic pump means and at least one hydraulic driving motor for tramming comprising the steps of: directing at least a major portion of the output of pressurized hydraulic fluid from said pump means to said driving motor for hydraulic energization thereof; directing a first control portion of such pressurized hydraulic fluid from said pump means to a first control valve means; selectively moving said first control valve means to vary the quantity of output of pressurized hydraulic fluid from said pump means; directing a second control portion of such pressurized fluid from said pump means to a second control valve means; selectively moving said second control valve means to limit the maximum quantity of output of pressurized hydraulic fluid from said pump means.

said first maximum output said directing of said second control portion of said pressurized hydraulic fluid is to a reservoir.

5. A method as specified in claim 3 wherein during said second maximum output said directing of said second control portion of said pressurized hydraulic fluid cooperates with said first control portion to limit said output of pressurized hydraulic fluid from said pump means to said second maximum output. 

1. A method of controlling the tramming rate of a mining machine having a constant speed hydraulic pump means and at least one hydraulic driving motor for tramming comprising the steps of: directing at least a major portion of the output of pressurized hydraulic fluid from said pump means to said driving motor for hydraulic energization thereof; directing a first control portion of such pressurized hydraulic fluid from said pump means to a first control valve means; selectively moving said first control valve means to vary the quantity of output of pressurized hydraulic fluid from said pump means; directing a second control portion of such pressurized fluid from said pump means to a second control valve means; selectively moving said second control valve means to limit the maximum quantity of output of pressurized hydraulic fluid from said pump means.
 2. The method as specified in claim 1 wherein said pump means includes a charge pump portion and said first and second control portions of pressurized hydraulic fluid are directed from the output of said charge pump portion.
 3. A method as specified in claim 1 wherein said second control portion selectively limits the quantity of said output from said pump means between a first maximum output and a second maximum output less than said first maximum output.
 4. A method as specified in claim 3 wherein during said first maximum output said directing of said second control portion of said pressurized hydraulic fluid is to a reservoir.
 5. A method as specified in claim 3 wherein during said second maximum output said directing of said second control portion of said pressurized hydraulic fluid cooperates with said first control portion to limit said output of pressurized hydraulic fluid from said pump means to said second maximum output. 